OFDM Carrier Frequency Offset Estimation

by Osesina, Olukayode Isaac; Zhang, Yafan; Pagoti, Shirisha

Abstract (Summary)

This thesis discusses and investigates the estimation of carrier offset frequency inorthogonal frequency division multiplexing (OFDM) mobile systems. The investigationstarts by using Mobile WiMAX wireless communication specifications describedin IEEE 802.16e as the primary system setup. Under this setup orthogonalfrequency division multiple access (OFDMA) is used as a physical layer scheme; italso involves the use of pilots in the OFDM symbol for channel estimation.Although OFDM is resistant to multipath fading, it requires a high degree of synchronisationto maintain sub-carrier orthogonality. Therefore the level of performanceof the system depends first on the accuracy in estimating the carrier frequencyoffset and then the estimation of the channel. Maximum likelihood estimatoris used for estimating carrier frequency offset; its performance under different conditionsfor example SNR, number of virtual carriers needed for estimation etc. aresimulated and compared with theoretical results. The optimality of IEEE 802.16especifications was also examined during the simulations and results analysis.